Expander for piston skirts



March 17, 1936. w J 1x 2,034,005

EXPANDER FOR PISTON SKIRTS Filed Jan. 14; 1935 PIE|. 1 FIE]7. L TlEl.

' INVENTOR. W717i? J 5m.

XMM

ATTORNEYfi.

Patented Mar. 17, 1936 UNITED STATES PATENT OFFICE 2,034,605 EXPANDEB FOR PISTON sxm'rs Walter J. s Indianapolis, Ind. Application January 14, 1935, SerialNo. 1,632

Claims.

It is the purpose of this invention to provide an expander of this general character in sections so as to render it easy to install and permit of aderted thereby. Such an expander may be of the character which completely encircles the interior of the skirt with apertures in the boss sections which encircle the bosses either freely so as not to engage therewith, or engages and bears directly upon the side surfaces of the bosses. On the other hand, the expander may be of that character which lies only upon one side of the boss to be yieldingly wedged between the skirt and the sides of the bosses. The boss sections mayor may not press against the boss or boss portions which include the struts and the expander may comprise from two to six sections.

The particular feature of the invention resides in forming the expander of a plurality of sections having therein edges abutting when assembled, and which may be formed on a bias to permit of a wedging action, thereby being adjustable so as of installation of the expander. Fig. 4 is a per spectiveview showing a portion of the expander. Fig. 5 is a plan view taken on the line 5 5.of Fig. 4. Fig. 6 is the same as Fig. 4 showing a modified form. Fig. 7 is a plan view taken on the line 1-1 of Fig. 6. Fig. 8 is a diagrammatical illustration of different arrangements of the expander in the piston.

In the drawing, onetype of piston is shown for illustration having the usual head Ill, ring grooves ll, lands i2 and a skirt l3. Immediately beneath the piston ring grooves there are cut a pair of slotted openings l4 which extend partly about the circumference of the piston and serve to increase the flexibility of the skirt. The skirt l3, as herein illustrated, is split by a slightly diago- 56 nal but substantially vertical cut l5 extending instability in respect to the expansive forces exto obtain the desired expansive pressure exerted from the bottom of the skirt into one of the slotted openings l4. The skirt i3-usually carries struts it which support the projections formed by piston pin bosses ll. However, the particular character of the piston forms no ,part of the 5 invention other than to be acted upon by the expander as, and forthe purpose well known in the art.

The expander in one embodiment of the invention comprises essentially a pair of boss sections 10,

I8, each of which is provided with an'aperture i9 adapted to encircle the bosses II or a corresponding concave edge adapted to bear against and embrace a portion of the side surface of the bosses l'l. 15 The section it may be considered as providing a support in which the expander proper is ad-' justably positioned to the extent of the expanding pressure desired. The expander 20, substantially of the character illustrated in. the above-men- 2 tioned patent, comprises a shell curved in cross section and provided, intermediate its edges and extending longitudinally and substantially centrally thereof, with a fold or expansion formation 2| adapted to partially span the slot I5 of the 25 piston skirt.

As shown in the diagrammatical illustrations in Fig. 8, various arrangements of the expander may be employed wherein the boss sections may span and encircle the bosses as shown in Figs. A 30 and B with the expander sections mounted on opposite sides thereof'so as to exert pressure between opposite sides of the piston. The expander sections may, on the other hand, only embrace a portion of the bosses to exert pressure 35 between the wall of the piston and the bosses, as shown in FigDC. It will be noted that the expander of Fig. A is of four sections; that of Fig. B of two sections; while that of Fig. C is of six sections.

Theboss sections it have their forward edge stamped with a folded S-curve to provide a longitudinal recess for the reception of the adjacent edge of the expander section, said recessed edge being indicated at 22. As illustrated herein, said 45 recessed edge is biased, extending slightly at an angle approaching the walls of the piston toward the top. The free side edges of the expander section 20 are correspondingly biased to extend at the same angle when in operative position. Thus, '50 the opposite side edges of the expander section 20 are adapted to slide and be embraced within the recessed edges 22 of the boss section. The upper corner of the expander-section is provided with a tooth-like projection 23 so positioned as I to extend over the top edge of the boss section and lock thereon as indicated in Figs. 2, 4 and 5. However, there may be formed in the recessed edge of the boss section adjacent the top thereof one or more perforations 24 for reception of and interlocking with projection 23 when it is determined for proper expansion pressure that the expander section may not be positioned so as to extend the full length of the boss section.

In the modified forms illustrated in Figs. 6 and 7, in lieu of the folded recessed edge 22, there may be provided a recess I22 in the expander sections II8 formed by securing side plates I25 thereon by rivets I 26. The adjacent and abutting edges of the expander section I20 and the boss section II8 may be formed with a plurality of toothed projections I23 in saw-tooth formation to permit the expander section to be slid upwardly with respect to the boss section and piston but be interlocked therewith to permit downward movement.

From the foregoing, it will be noted that in any of the arrangements of the expanders as suggested by the illustrations of Fig. 8, or in the modified forms herein referred to, installation of the expander willbe simplified. Thus, the boss section is first mounted within the piston and held in place about or against the piston pin bosses whereupon the expander section may be inserted from the underside of the piston so as to bear between the piston wall and have its edges engaged in the recessed edges of the boss section in the manner illustrated in Fig. 3. By tapping the lower end of the expander section, it may be forced and wedged upwardly until the desired expanding pressure is attained to cause the desired expansion of the piston skirt. Depending upon the relative position of the expander section in respect to the boss section and skirt, and within limits, various pressures and expansions may be readily obtained. The inventhe piston, and, therefore, the amount of expension of the piston skirt.

The invention claimed is:

1. The combination with a piston having a skirt and piston pin boss portions, of a piston skirt expander comprising boss sections associated with the piston pin boss portions, an expander section removably associated with said boss sections mounted under spring tension between said sections and the piston skirt for exerting an expansive pressure thereagainst, abutting edges of said sections extending upwardly at an angle away from the plane through the center of the piston and boss axes, and means formed thereon to permit slidable interlocking thereof, whereby the yielding pressure of the expander section against the piston skirt will be increased as it approaches alignment with the boss section.

2. The combination with a piston having a skirt and piston pin boss portions, of a piston skirt expander comprising boss'sections associated with the piston pin boss portions, an expander section removably associat d with said boss sections mounted under sp tension between said sections and the piston skirt for exerting an expansive pressure thereagainst, and a plurality of ratchet teeth formed along the abutting edge of one of said members arranged to permit relative sliding movement therebetween when inserting the expander section in place while interlocking to prevent disengagement thereof.

3. The combination with a piston having a skirt and piston pin boss portion, of a piston skirt expander comprising boss sections adapted to interlock with the pistonpin boss portions, each of said sections having a grooved edge extending at an angle to the vertical axis thereof and sloping from the upper portion toward the lower portion of the piston, and an expander section formed of sheet metal and having an expansive formation therein provided with free edges extending at an angle corresponding to the grooved edges of the boss sections for slidable engagement therein, said expander section being slidable upwardly within the piston so as to be wedged and compressed under its inherent spring tension between the skirt and boss sections, its compression being increased as it is forced upwardly into expanding position.

4. The combination with a piston having a skirt and piston pin boss portion, of a piston skirt expander comprising boss sections adapted to interlock with the piston pin boss portions, each of said sections having a grooved edge extending at an angle to the vertical axis thereof and sloping from the upper portion toward the lower portion of the piston, an expander section formed of sheet metal and having an expansive formation therein provided with free edges extending at an angle corresponding to the grooved edges of the boss sections for slidable engagement therein, said expander section being slidable upwardly within the piston so as to be wedged and compressed under its inherent spring tension between the skirt and boss sections, its compression being increased as it is forced upwardly into expanding position, and means on the adjacent edges of said sections for interlocking with the other sections to prevent the releasing thereof.

5. The combination with a piston having a skirt and piston pin boss portion, of a piston skirt expander comprising boss sections adapted to interlock with the piston pin boss portions, each of said sections having a grooved edge extending at an angle to the vertical axis thereof and sloping from the upper portion toward the lower portion of the piston, an expander section formed of sheet metal and having an expansive formation therein provided with free edges extending atan angle corresponding to the grooved edges of the boss sections for slidable engagement therein, said expander section being slidable upwardly within the piston so as to be wedged and compressed under its inherent spring tension between the skirt and boss sections, its

compression being increased as it is forced upwardly into expanding position, and a plurality of protruding saw teeth provided on the abutting edge of one of said sections for interlocking with the other sections to prevent the release thereof.

- WALTER J. SIX. 

